The present invention relates to a ghost canceling apparatus used in a satellite station, a head-end demodulator section of a CATV system, and a consumer television set, particularly to a ghost canceling apparatus using a transversal filter, an input signal of the ghost canceling apparatus being either modulated or a demodulated television signal.
Lately, the ghost canceling apparatus using a transversal filter has become considered to be useful for canceling ghosts. The principle of this ghost canceling apparatus is that the ghost canceling apparatus generates the reverse transfer function to the propagation path which is including a ghost. The ghost canceling apparatus using a transversal filter is described by W. Ciciora, "A Tutorial on Ghost Cancelling in Television Systems", IEEE Trans. on Consumer Electronics, Vol CE-25, February 1979, and by J. Murakami, "A Digitalized Automatic Ghost Canceller", IEEE Trans. on Consumer Electronics, Vol CE-25, August 1979.
As the algorithm for controlling tap gains of the transversal filter, the Zero-Forcing algorithm and the Mean Square Error algorithm is usually used, and as the reference signal for canceling the ghost, a differentiated vertical pulse is usually used.
The ghost canceling apparatus using the transversal filter, the abovesaid algorithm, and the abovesaid reference signal can't completely cancel a higher frequency component of the ghost, especially a color ghost.